FIGS. 1A and 1B depict a portion of a conventional energy assisted magnetic recording (EAMR) transducer 10. The conventional EAMR transducer 10 includes a conventional waveguide 12 having a conventional core 18 and cladding 14 and 16, a grating 20, a conventional near-field transducer (NFT) 30, and a write pole 40. The NFT 30 has a disk portion 34 and a pin portion 32. The pin portion 32 is between the disk portion 34 and the air-bearing surface (ABS). The conventional EAMR transducer 10 is used in writing to a recording media and receives light, or energy, from a conventional laser (not shown).
In operation, light from a laser is coupled to the waveguide 12. Light is guided by the conventional waveguide 12 to the NFT 30 near the ABS. The NFT 30 utilizes local resonances in surface plasmons to focus the light to magnetic recording media (not shown), such as a disk. The surface plasmons used by the NFT 30 are electromagnetic waves that propagate along metal/dielectric interfaces. At resonance, the NFT 30 couples the optical energy of the surface plasmons efficiently into the recording medium layer with a confined optical spot which is much smaller than the optical diffraction limit. This optical spot can typically heat the recording medium layer above the Curie point in nano-seconds. High density bits can be written on a high coercivity medium with a pole 40 having relatively modest magnetic field.
Although the EAMR transducer 10 may use the conventional NFT 30 in recording data to a media, there are drawbacks. FIGS. 2A and 2B depict the conventional EAMR transducer 10 during use and illustrate one such drawback. During operation, a significant amount of the light energy from the laser is lost in the form of local heating of the NFT 30. Some estimates indicate that the temperature of the EAMR transducer 10 in the vicinity of the NFT 30 may be approximately two hundred degrees centigrade. At such elevated operating temperatures, a portion of the NFT 30 may protrude from the ABS. This is shown in FIGS. 2A and 2B, particularly by portion 33 of the NFT 30. At the higher operating temperatures of the transducer 10, the pin 32 of the NFT may undergo elastic deformation and plastic deformation. These deformations may be due to the combination of high internal stress and softening of the NFT material (i.e. Au). As a result, the portion 33 of the pin 32 protrudes from the ABS. Although the elastic portion of the deformation may be at least partially corrected by reducing the temperature, the plastic portion of the deformation may not be. Further, the protrusion may be significant. In some cases, portion 33 of the NFT 30 may protrudes several nanometers from the ABS. Because of the low fly height of the conventional transducer 10, this protrusion 33 may result in the NFT 30 contacting the disk. As a result, a portion of the NFT 30 may be ground away, which adversely affects performance and reliability of the transducer 10.
Conventional mechanisms for addressing the protrusion 33 of the NFT 30 may include selecting the materials used for the NFT 30 to increase the hardness and/or increase the temperature at which the material softens. Such changes may reduce the efficiency of the NFT, which is undesirable. Further, it may be difficult to find a material that has the required mechanical stability and optical efficiency at elevated temperature.
Accordingly, what is needed is a system and method for improving reliability of an EAMR transducer.